WO2021006055A1 - 弾性波装置、高周波フロントエンド回路及び通信装置 - Google Patents

弾性波装置、高周波フロントエンド回路及び通信装置 Download PDF

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Publication number
WO2021006055A1
WO2021006055A1 PCT/JP2020/025013 JP2020025013W WO2021006055A1 WO 2021006055 A1 WO2021006055 A1 WO 2021006055A1 JP 2020025013 W JP2020025013 W JP 2020025013W WO 2021006055 A1 WO2021006055 A1 WO 2021006055A1
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Prior art keywords
elastic wave
piezoelectric layer
wave device
support substrate
filter
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PCT/JP2020/025013
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English (en)
French (fr)
Japanese (ja)
Inventor
英樹 岩本
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株式会社村田製作所
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Application filed by 株式会社村田製作所 filed Critical 株式会社村田製作所
Priority to JP2021530593A priority Critical patent/JP7510416B2/ja
Priority to KR1020217041248A priority patent/KR20220008345A/ko
Priority to CN202080042328.3A priority patent/CN113940002A/zh
Publication of WO2021006055A1 publication Critical patent/WO2021006055A1/ja
Priority to US17/567,918 priority patent/US12009799B2/en

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/25—Constructional features of resonators using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02543—Characteristics of substrate, e.g. cutting angles
    • H03H9/02551—Characteristics of substrate, e.g. cutting angles of quartz substrates
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02015—Characteristics of piezoelectric layers, e.g. cutting angles
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02228—Guided bulk acoustic wave devices or Lamb wave devices having interdigital transducers situated in parallel planes on either side of a piezoelectric layer
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02543—Characteristics of substrate, e.g. cutting angles
    • H03H9/02559—Characteristics of substrate, e.g. cutting angles of lithium niobate or lithium-tantalate substrates
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02543—Characteristics of substrate, e.g. cutting angles
    • H03H9/02574—Characteristics of substrate, e.g. cutting angles of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/64—Filters using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/64—Filters using surface acoustic waves
    • H03H9/6423—Means for obtaining a particular transfer characteristic
    • H03H9/6433—Coupled resonator filters
    • H03H9/6483—Ladder SAW filters

Definitions

  • the present invention generally relates to elastic wave devices, high-frequency front-end circuits and communication devices, and more specifically, elastic wave devices including support substrates and piezoelectric layers, high-frequency front-end circuits including elastic wave devices, and high-frequency front ends.
  • the present invention relates to a communication device including a circuit.
  • an elastic wave device including a support substrate and a piezoelectric layer is known (see, for example, Patent Document 1).
  • the elastic wave device described in Patent Document 1 is formed on a support substrate made of quartz, a piezoelectric layer made of LiTaO 3 (lithium tantalate) laminated on the support substrate, and a piezoelectric layer. It is provided with an IDT electrode.
  • spurious in Rayleigh mode is generated in the vicinity of 0.7 times the pass band of the elastic wave device itself depending on the polarization direction or the cut angle of the piezoelectric layer. It may cause deterioration of the characteristics of the elastic wave device.
  • the present invention has been made in view of the above points, and an object of the present invention is to provide an elastic wave device, a high-frequency front-end circuit, and a communication device capable of reducing spurious.
  • the elastic wave device includes a support substrate, a piezoelectric layer, and an IDT electrode.
  • the support substrate is made of quartz.
  • the piezoelectric layer is formed on the support substrate and is made of LiTaO 3 .
  • the IDT electrode is formed on the piezoelectric layer and has a plurality of electrode fingers.
  • the IDT electrode is formed on the negative surface side of the piezoelectric layer.
  • the cut angle of the piezoelectric layer is 39 ° Y or more and 48 ° Y or less.
  • the high frequency front-end circuit includes a filter and an amplifier circuit.
  • the filter includes the elastic wave device and passes a high frequency signal in a predetermined frequency band.
  • the amplifier circuit is connected to the filter and amplifies the amplitude of the high frequency signal.
  • the communication device includes the high frequency front end circuit and a signal processing circuit.
  • the signal processing circuit processes the high frequency signal.
  • the elastic wave device According to the elastic wave device, the high frequency front end circuit and the communication device according to the above aspect of the present invention, spurious can be reduced.
  • FIG. 1 is a circuit diagram of an elastic wave device according to an embodiment.
  • FIG. 2 is a configuration diagram of a communication device including the same elastic wave device.
  • FIG. 3 is a cross-sectional view of the elastic wave device of the same as above.
  • FIG. 4A is a plan view of a main part of the elastic wave device of the same as above.
  • FIG. 4B is a sectional view taken along line X1-X1 of FIG. 4A.
  • FIG. 5 is a graph showing the relationship between the cut angle of the piezoelectric layer and the phase characteristics of the Rayleigh mode.
  • FIG. 6 is a graph showing the relationship between the cut angle of the piezoelectric layer and TCF.
  • FIG. 7 is a cross-sectional view of an elastic wave device according to a modified example of the embodiment.
  • FIG. 4A, FIG. 4B, and FIG. 7 referred to in the following embodiments and the like are schematic views, and the size and thickness ratios of the respective components in the drawings are not necessarily the actual dimensional ratios. It does not always reflect.
  • the elastic wave device 1 As shown in FIG. 1, the elastic wave device 1 according to the embodiment has a first terminal 101 and a first terminal 101 electrically connected to an external antenna 200 of the elastic wave device 1. It is provided between the second terminal 102 and the second terminal 102, which is different from the above.
  • the elastic wave device 1 is a ladder type filter and includes a plurality of (for example, nine) elastic wave resonators 31 to 39.
  • the plurality of elastic wave resonators 31 to 39 are a plurality of (for example, five) series arm resonators (elastic wave resonators 31) provided on the first path r1 connecting the first terminal 101 and the second terminal 102.
  • a plurality (for example, four) of parallel arm resonators (elastic wave resonators 32, 34, 36, 38) provided on r23 and r24 are included.
  • an element having a function as an inductor or a capacitor may be arranged on the first path r1 as an element other than the series arm resonator.
  • an element having a function as an inductor or a capacitor as an element other than the parallel arm resonator may be arranged on each of the second paths r21, r22, r23, and r24.
  • the multiplexer 100 includes a first filter 21 including a first terminal 101, a second terminal 102, a third terminal 103, and an elastic wave device 1. , A second filter 22 and the like.
  • the first terminal 101 is an antenna terminal that can be electrically connected to the external antenna 200 of the multiplexer 100.
  • the first filter 21 is a first receiving filter including an elastic wave device 1 and provided between the first terminal 101 and the second terminal 102.
  • the first filter 21 passes a high frequency signal in a predetermined first frequency band and attenuates a signal other than the first frequency band.
  • the second filter 22 is a second reception filter provided between the first terminal 101 and the third terminal 103.
  • the second filter 22 passes a high frequency signal in a predetermined second frequency band and attenuates a signal other than the second frequency band.
  • the first filter 21 and the second filter 22 have different pass bands.
  • the pass band of the first filter 21 is a lower frequency band than the pass band of the second filter 22. Therefore, in the multiplexer 100, the pass band of the second filter 22 is on the higher frequency side than the pass band of the first filter 21.
  • the maximum frequency of the pass band of the first filter 21 is lower than the minimum frequency of the pass band of the second filter 22.
  • the first filter 21 and the second filter 22 are connected to a common first terminal 101.
  • the multiplexer 100 further includes a fourth terminal 104, a fifth terminal 105, a third filter 23, and a fourth filter 24.
  • the fourth terminal 104, the fifth terminal 105, the third filter 23, and the fourth filter 24 are not essential components.
  • the third filter 23 is a first transmission filter provided between the first terminal 101 and the fourth terminal 104.
  • the third filter 23 passes a high frequency signal in a predetermined third frequency band and attenuates a signal other than the third frequency band.
  • the fourth filter 24 is a second transmission filter provided between the first terminal 101 and the fifth terminal 105.
  • the fourth filter 24 passes a high frequency signal in a predetermined fourth frequency band and attenuates a signal other than the fourth frequency band.
  • the high frequency front end circuit 300 includes a multiplexer 100, a first amplifier circuit 303, and a first switch circuit 301. Further, the high frequency front end circuit 300 further includes a second amplifier circuit 304 and a second switch circuit 302. However, in the high frequency front end circuit 300, the second amplifier circuit 304 and the second switch circuit 302 are not essential components.
  • the first amplifier circuit 303 is electrically connected to the first filter 21 and the second filter 22 of the multiplexer 100. More specifically, the first amplifier circuit 303 is connected to the first filter 21 and the second filter 22 via the first switch circuit 301. The first amplifier circuit 303 amplifies and outputs a high frequency signal (received signal) that has passed through the antenna 200, the multiplexer 100, and the first switch circuit 301.
  • the first amplifier circuit 303 is a low noise amplifier circuit.
  • the first switch circuit 301 has two selected terminals individually connected to the second terminal 102 and the third terminal 103 of the multiplexer 100, and a common terminal connected to the first amplifier circuit 303. That is, the first switch circuit 301 is connected to the first filter 21 via the second terminal 102, and is connected to the second filter 22 via the third terminal 103.
  • the first switch circuit 301 is composed of, for example, a SPDT (Single Pole Double Throw) type switch.
  • the first switch circuit 301 is controlled by a control circuit (not shown).
  • the first switch circuit 301 connects the common terminal and the selected terminal according to the control signal from the control circuit.
  • the first switch circuit 301 may be configured by a switch IC (Integrated Circuit).
  • the number of selected terminals connected to the common terminals is not limited to one, and may be plural. That is, the high-frequency front-end circuit 300 may be configured to correspond to carrier aggregation.
  • the second amplifier circuit 304 amplifies the high frequency signal (transmission signal) output from the outside of the high frequency front end circuit 300 (for example, the RF signal processing circuit 402 described later), and passes through the second switch circuit 302 and the multiplexer 100. Is output to the antenna 200.
  • the second amplifier circuit 304 is a power amplifier circuit.
  • the second switch circuit 302 is composed of, for example, a SPDT (Single Pole Double Throw) type switch.
  • the second switch circuit 302 is controlled by the control circuit.
  • the second switch circuit 302 connects the common terminal and the selected terminal according to the control signal from the control circuit.
  • the second switch circuit 302 may be configured by a switch IC (Integrated Circuit). In the second switch circuit 302, the number of selected terminals connected to the common terminals is not limited to one, and may be plural.
  • the communication device 400 includes a high-frequency front-end circuit 300 and a signal processing circuit 401.
  • the signal processing circuit 401 processes a high frequency signal.
  • the signal processing circuit 401 includes an RF signal processing circuit 402 and a baseband signal processing circuit 403.
  • the baseband signal processing circuit 403 is not an essential component.
  • the RF signal processing circuit 402 processes the high frequency signal received by the antenna 200.
  • the high frequency front end circuit 300 transmits a high frequency signal (received signal, transmitted signal) between the antenna 200 and the RF signal processing circuit 402.
  • the RF signal processing circuit 402 is, for example, an RFIC (Radio Frequency Integrated Circuit), and performs signal processing on a high frequency signal (received signal). For example, the RF signal processing circuit 402 performs signal processing such as down-conversion on a high-frequency signal (received signal) input from the antenna 200 via the high-frequency front-end circuit 300, and the received signal generated by the signal processing. Is output to the baseband signal processing circuit 403.
  • the baseband signal processing circuit 403 is, for example, a BBIC (Baseband Integrated Circuit).
  • the received signal processed by the baseband signal processing circuit 403 is used, for example, for image display as an image signal or for a telephone call as an audio signal.
  • the RF signal processing circuit 402 performs signal processing such as up-conversion on the high frequency signal (transmission signal) output from the baseband signal processing circuit 403, and uses the high frequency signal for which the signal processing has been performed as a second signal. Output to the amplification circuit 304.
  • the baseband signal processing circuit 403 performs predetermined signal processing on a transmission signal from the outside of the communication device 400, for example.
  • the elastic wave device 1 includes a support substrate 4, a piezoelectric layer 6, and an IDT (Interdigital Transducer) electrode 7.
  • IDT Interdigital Transducer
  • the support substrate 4 is a substrate made of quartz. More specifically, the support substrate 4 supports the piezoelectric layer 6 and the IDT electrode 7. In the support substrate 4, the sound velocity of the bulk wave propagating is higher than the sound velocity of the elastic wave propagating in the piezoelectric layer 6. In the support substrate 4, the sound velocity of the lowest sound velocity bulk wave among the plurality of bulk waves propagating therein is higher than the sound velocity of the elastic wave propagating in the piezoelectric layer 6.
  • Each of the plurality of elastic wave resonators 3 is a 1-port type elastic wave resonator provided with reflectors (for example, short-circuit grating) on both sides of the IDT electrode 7 in the elastic wave propagation direction. However, the reflector is not essential.
  • the elastic wave resonator 3 is not limited to the 1-port type elastic wave resonator, and may be, for example, a vertically coupled elastic wave resonator composed of a plurality of IDT electrodes.
  • the piezoelectric layer 6 is directly laminated on the support substrate 4.
  • the piezoelectric layer 6 has a first main surface 61 on the IDT electrode 7 side and a second main surface 62 on the support substrate 4 side.
  • the piezoelectric layer 6 is formed on the support substrate 4 so that the second main surface 62 is on the support substrate 4 side.
  • the piezoelectric layer 6 is formed on the support substrate 4 and is made of LiTaO 3 (lithium tantalate). More specifically, the piezoelectric layer 6 is, for example, a ⁇ ° Y-cut X-propagated LiTaO 3 piezoelectric single crystal.
  • the ⁇ ° Y-cut X propagation LiTaO 3 piezoelectric single crystal has the X axis as the central axis in the direction from the Y axis to the Z axis when the three crystal axes of the LiTaO 3 piezoelectric single crystal are the X axis, the Y axis, and the Z axis.
  • ⁇ ° is, for example, 39 ° or more and 48 ° or less.
  • the piezoelectric layer 6 is not limited to the ⁇ ° Y-cut X-propagated LiTaO 3 piezoelectric single crystal, and may be, for example, ⁇ ° Y-cut X-propagated LiTaO 3 piezoelectric ceramics.
  • the elastic wave resonator 3 in the elastic wave device 1 there are a longitudinal wave, an SH wave, an SV wave, or a mode in which these are combined as a mode of the elastic wave propagating in the piezoelectric layer 6.
  • a mode containing an SH wave as a main component is used as a main mode.
  • the higher-order mode is a spurious mode generated on the higher frequency side than the main mode of the elastic wave propagating in the piezoelectric layer 6.
  • the mode of the elastic wave propagating in the piezoelectric layer 6 is "the mode mainly composed of SH waves is the main mode"
  • the parameters of the piezoelectric layer 6 material, Euler angles, thickness, etc.
  • the parameters of the IDT electrode 7 material, thickness, electrode finger period, etc.
  • Euler angles of the piezoelectric layer 6 can be determined by analysis.
  • the single crystal material and cut angle of the piezoelectric layer 6 may be appropriately determined according to, for example, the required specifications of the filter (passing characteristics, attenuation characteristics, temperature characteristics, filter characteristics such as bandwidth) and the like. ..
  • the thickness of the piezoelectric layer 6 is 3.5 ⁇ or less, where ⁇ is the wavelength of the elastic wave determined by the electrode finger period of the IDT electrode 7.
  • the electrode finger cycle is a cycle of a plurality of electrode fingers 72 of the IDT electrode 7. As a result, the Q value can be increased.
  • the thickness of the piezoelectric layer 6 is 2.5 ⁇ or less.
  • the TCF Temporal Coefficients of Frequency
  • the thickness of the piezoelectric layer 6 is 1.5 ⁇ or less. This makes it possible to adjust the electromechanical coupling coefficient in a wide range. More preferably, the thickness of the piezoelectric layer 6 is 0.05 ⁇ or more and 0.5 ⁇ or less. This makes it possible to adjust the electromechanical coupling coefficient in a wider range.
  • the IDT electrode 7 is formed on the piezoelectric layer 6.
  • the term "formed on the piezoelectric layer 6" includes a case where it is formed directly on the piezoelectric layer 6 and a case where it is indirectly formed on the piezoelectric layer 6.
  • the IDT electrode 7 is located on the side opposite to the support substrate 4 with the piezoelectric layer 6 interposed therebetween.
  • the IDT electrode 7 can be formed of an appropriate metal material such as Al, Cu, Pt, Au, Ag, Ti, Ni, Cr, Mo, W or an alloy mainly composed of any of these metals. Further, the IDT electrode 7 may have a structure in which a plurality of metal films made of these metals or alloys are laminated.
  • the IDT electrode 7 is an Al film, but is not limited to this.
  • a main electrode composed of an adhesive film made of a Ti film formed on the piezoelectric layer 6 and an Al film formed on the adhesive film. It may be a laminated film with a film.
  • the thickness of the adhesive film is, for example, about 10 nm.
  • the thickness of the main electrode film is, for example, about 130 nm.
  • the IDT electrode 7 has a plurality of bus bars 71 and a plurality of electrode fingers 72, as shown in FIGS. 4A and 4B.
  • the plurality of bus bars 71 include a first bus bar 711 and a second bus bar 712.
  • the plurality of electrode fingers 72 include a plurality of first electrode fingers 721 and a plurality of second electrode fingers 722.
  • the support substrate 4 is not shown.
  • the first bus bar 711 and the second bus bar 712 are elongated with the second direction D2 (X-axis direction) orthogonal to the first direction D1 ( ⁇ ° Y direction) along the thickness direction of the support substrate 4 as the longitudinal direction. It is in the shape.
  • the first bus bar 711 and the second bus bar 712 face each other in the third direction D3 orthogonal to both the first direction D1 and the second direction D2.
  • a plurality of first electrode fingers 721 are connected to the first bus bar 711 and extend toward the second bus bar 712.
  • the plurality of first electrode fingers 721 extend from the first bus bar 711 along the third direction D3.
  • the tips of the plurality of first electrode fingers 721 and the second bus bar 712 are separated from each other.
  • the plurality of first electrode fingers 721 have the same length and width as each other.
  • the plurality of second electrode fingers 722 are connected to the second bus bar 712 and extend toward the first bus bar 711.
  • the plurality of second electrode fingers 722 extend from the second bus bar 712 along the third direction D3.
  • the tips of the plurality of second electrode fingers 722 are separated from the first bus bar 711.
  • the plurality of second electrode fingers 722 have the same length and width as each other.
  • the length and width of the plurality of second electrode fingers 722 are the same as the length and width of the plurality of first electrode fingers 721, respectively.
  • the electrode finger cycle of the IDT electrode 7 is the distance between the adjacent sides of the adjacent first electrode finger 721 and the second electrode finger 722.
  • the electrode finger cycle of the IDT electrode 7 is (when the width of the first electrode finger 721 or the second electrode finger 722 is W1 and the space width between the adjacent first electrode finger 721 and the second electrode finger 722 is S1. It is defined by W1 + S1).
  • the duty ratio which is the value obtained by dividing the electrode finger width W1 by the electrode finger cycle, is defined by W1 / (W1 + S1).
  • the duty ratio is, for example, 0.5.
  • ⁇ is defined by the repetition period P1 of the plurality of first electrode fingers 721 and the plurality of second electrode fingers 722.
  • a group of electrode fingers (plurality of electrode fingers 72) including a plurality of first electrode fingers 721 and a plurality of second electrode fingers 722 includes a plurality of first electrode fingers 721 and a plurality of second electrode fingers 722.
  • the configuration may be such that the plurality of first electrode fingers 721 and the plurality of second electrode fingers 722 are alternately arranged but separated from each other. For example, a region in which the first electrode finger 721 and the second electrode finger 722 are lined up one by one, and a region in which the first electrode finger 721 or the second electrode finger 722 are lined up in the second direction D2. And may be mixed.
  • the number of each of the plurality of first electrode fingers 721 and the plurality of second electrode fingers 722 in the IDT electrode 7 is not particularly limited.
  • the IDT electrode 7 is formed on the negative surface side of the piezoelectric layer 6 as shown in FIG. More specifically, in the piezoelectric layer 6, the first main surface 61 is a negative surface and the second main surface 62 is a positive surface. In other words, the piezoelectric layer 6 is formed on the support substrate 4 so that the first main surface 61 is a negative surface and the second main surface 62 is a positive surface. The IDT electrode 7 is formed on the first main surface 61, that is, the minus surface of the piezoelectric layer 6.
  • the cut angle of the piezoelectric layer 6 is 39 ° Y or more and 48 ° Y or less. As shown in FIG. 5, when the cut angle of the piezoelectric layer 6 is 39 ° Y or more and 48 ° Y or less, the cut angle of the piezoelectric layer 6 is less than 39 ° Y, and the cut angle of the piezoelectric layer 6 The phase characteristics are superior as compared with the case where is larger than 48 ° Y.
  • the cut angle of the piezoelectric layer 6 is 42 ° Y or more.
  • the TCF can be reduced.
  • the absolute value of TCF can be 5 ppm / ° C or less.
  • the cut angle of the piezoelectric layer 6 is 44 ° Y or more.
  • the TCF can be made smaller.
  • the absolute value of TCF can be 2 ppm / ° C or less.
  • the sound velocity of the slow transverse wave propagating on the support substrate 4 is 3950 m / s or more. More specifically, the sound velocity of the slow transverse wave propagating through the support substrate 4 is higher than the resonance sound velocity of 3800 m / s and is antiresonant sound velocity of 3950 m / s or more. Thereby, good resonance characteristics and anti-resonance characteristics can be obtained.
  • the speed of sound of the slow transverse wave propagating on the support substrate 4 is 4100 m / s or more. More specifically, the sound velocity of the slow transverse wave propagating on the support substrate 4 is the difference (150 m / s) between the anti-resonant sound velocity of 3950 m / s and the resonance sound velocity of 3800 m / s and the anti-resonant sound velocity of 3950 m / s. The sum is 4100 m / s or more. As a result, the characteristics of the ladder type filter can be improved.
  • the angles formed by the support substrate 4 and the Z axis and the X axis (second direction D2) of the LiTaO 3 are parallel.
  • the Z axis of the support substrate 4 and the direction in which the plurality of electrode fingers 72 of the IDT electrode 7 are arranged (second direction D2) are parallel.
  • the IDT electrode 7 is formed on the negative surface side of the piezoelectric layer 6, and the cut angle of the piezoelectric layer 6 is 39 ° Y or more and 48 ° Y or less. Is. As a result, spurious can be reduced.
  • the sound velocity of the support substrate 4 is 3950 m / s. Thereby, good resonance characteristics and anti-resonance characteristics can be obtained. As a result, the characteristics of the ladder type filter can be improved.
  • the angle formed by the Z axis of the support substrate 4 and the X axis (second direction D2) of the LiTaO 3 is ⁇ 20 ° or less.
  • the speed of sound of slow transverse waves can be increased to 4100 m / s or more.
  • the Z axis of the support substrate 4 and the X axis (second direction D2) of the LiTaO 3 are parallel. As a result, Z propagation can be achieved, so that high sound velocity can be realized on the support substrate 4.
  • the cut angle of the piezoelectric layer 6 is 42 ° Y or more.
  • the TCF can be reduced.
  • the absolute value of TCF can be 5 ppm / ° C or less.
  • the cut angle of the piezoelectric layer 6 is 44 ° Y or more.
  • the TCF can be made smaller.
  • the absolute value of TCF can be 2 ppm / ° C or less.
  • the piezoelectric layer 6 is directly laminated on the support substrate 4. As a result, spurious emissions can be further reduced, and deterioration of characteristics can be suppressed.
  • the thickness of the piezoelectric layer 6 is 3.5 ⁇ or less. As a result, the Q value can be increased.
  • the thickness of the piezoelectric layer 6 is 2.5 ⁇ or less. Thereby, TCF can be improved.
  • the thickness of the piezoelectric layer 6 is 1.5 ⁇ or less. This makes it possible to adjust the electromechanical coupling coefficient in a wide range.
  • the thickness of the piezoelectric layer 6 is 0.05 ⁇ or more and 0.5 ⁇ or less. This makes it possible to adjust the electromechanical coupling coefficient in a wider range.
  • the piezoelectric layer 6 is not limited to being directly laminated on the support substrate 4, and may be indirectly formed on the support substrate 4. In other words, as shown in FIG. 7, another layer may be present between the piezoelectric layer 6 and the support substrate 4.
  • the bass velocity film 5 may be formed on the support substrate 4, and the piezoelectric layer 6 may be formed on the bass velocity film 5.
  • the elastic wave device 1a includes a support substrate 4, a bass velocity film 5, a piezoelectric layer 6, and an IDT electrode 7.
  • the bass velocity film 5 is a film in which the sound velocity of the bulk wave propagating in the bass velocity film 5 is lower than the sound velocity of the bulk wave propagating in the piezoelectric layer 6.
  • the bass velocity film 5 is provided between the support substrate 4 and the piezoelectric layer 6. Since the low sound velocity film 5 is provided between the support substrate 4 and the piezoelectric layer 6, the sound velocity of the elastic wave is lowered.
  • Elastic waves concentrate energy in a medium that is essentially low sound velocity. Therefore, it is possible to enhance the effect of confining the energy of the elastic wave in the piezoelectric layer 6 and in the IDT electrode 7 in which the elastic wave is excited. As a result, the loss can be reduced and the Q value can be increased as compared with the case where the bass velocity film 5 is not provided.
  • the material of the bass velocity film 5 is, for example, silicon oxide.
  • the material of the bass velocity film 5 is not limited to silicon oxide, and is mainly composed of glass, silicon nitride, tantalum oxide, a compound obtained by adding fluorine, carbon, or boron to silicon oxide, or each of the above materials. It may be a material.
  • the temperature characteristics can be improved.
  • the elastic constant of LiTaO 3 which is the material of the piezoelectric layer 6, has a negative temperature characteristic, and the temperature characteristic of silicon oxide has a positive temperature characteristic. Therefore, in the elastic wave device 1, the absolute value of TCF can be reduced. Further, the intrinsic acoustic impedance of silicon oxide is smaller than the intrinsic acoustic impedance of LiTaO 3 , which is the material of the piezoelectric layer 6. Therefore, it is possible to both increase the electromechanical coupling coefficient, that is, expand the specific band, and improve the frequency temperature characteristic.
  • the thickness of the bass velocity film 5 is preferably 2.0 ⁇ or less.
  • the film stress can be reduced, and as a result, the warp of the wafer can be reduced, the non-defective rate can be improved, and the characteristics can be stabilized. It becomes. Further, if the thickness of the bass velocity film 5 is within the range of 0.1 ⁇ or more and 0.5 ⁇ or less, the electromechanical coupling coefficient hardly changes.
  • the support substrate 4 and the piezoelectric layer 6 are not limited to having one layer (bass sound velocity film 5) as described above, and a plurality of layers may be laminated.
  • the elastic wave device 1a according to the above modification also has the same effect as the elastic wave device 1 according to the embodiment.
  • the elastic wave device (1; 1a) includes a support substrate (4), a piezoelectric layer (6), and an IDT electrode (7).
  • the support substrate (4) is made of quartz.
  • the piezoelectric layer (6) is formed on the support substrate (4) and is made of LiTaO 3 .
  • the IDT electrode (7) is formed on the piezoelectric layer (6) and has a plurality of electrode fingers (72).
  • the IDT electrode (7) is formed on the negative surface side of the piezoelectric layer (6).
  • the cut angle of the piezoelectric layer (6) is 39 ° Y or more and 48 ° Y or less. According to the elastic wave device (1; 1a) according to the first aspect, spurious can be reduced.
  • the sound velocity of the slow transverse wave propagating on the support substrate (4) is 3950 m / s or more. According to the elastic wave device (1; 1a) according to the second aspect, good resonance characteristics and antiresonance characteristics can be obtained.
  • the sound velocity of the slow transverse wave propagating on the support substrate (4) is 4100 m / s or more.
  • the characteristics of the ladder type filter can be improved.
  • the Z-axis of the support substrate (4) and the X-axis of the LiTaO 3 (second direction D2) The angle between the two is ⁇ 20 ° or less.
  • the sound velocity of a slow transverse wave can be set to 4100 m / s or more.
  • the Z-axis of the support substrate (4) and the X-axis of the LiTaO 3 (second direction D2) are parallel. According to the elastic wave device (1; 1a) according to the fifth aspect, since Z propagation can be performed, high sound velocity can be realized on the support substrate (4).
  • the cut angle of the piezoelectric layer (6) is 42 ° Y or more in any one of the first to fifth aspects.
  • the TCF can be reduced.
  • the absolute value of TCF can be 5 ppm / ° C or less.
  • the cut angle of the piezoelectric layer (6) is 44 ° Y or more in the sixth aspect.
  • the TCF can be made smaller.
  • the absolute value of TCF can be 2 ppm / ° C or less.
  • the piezoelectric layer (6) is directly laminated on the support substrate (4). According to the elastic wave device (1) according to the eighth aspect, spurious can be further reduced, so that deterioration of characteristics can be suppressed.
  • the high-frequency front-end circuit (300) includes a filter (first filter 21; second filter 22; third filter 23; fourth filter 24) and an amplifier circuit (first amplifier circuit 303; second filter). It is provided with an amplifier circuit 304).
  • the filter includes an elastic wave device (1; 1a) according to any one of the first to eighth aspects, and passes a high frequency signal in a predetermined frequency band.
  • the amplifier circuit is connected to a filter and amplifies the amplitude of the high frequency signal. According to the high frequency front-end circuit (300) according to the ninth aspect, spurious can be reduced in the elastic wave device (1; 1a).
  • the communication device (400) according to the tenth aspect includes the high frequency front end circuit (300) of the ninth aspect and the signal processing circuit (401).
  • the signal processing circuit (401) processes a high frequency signal. According to the communication device (400) according to the tenth aspect, spurious can be reduced in the elastic wave device (1; 1a).

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
PCT/JP2020/025013 2019-07-05 2020-06-25 弾性波装置、高周波フロントエンド回路及び通信装置 WO2021006055A1 (ja)

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JP2021530593A JP7510416B2 (ja) 2019-07-05 2020-06-25 弾性波装置、高周波フロントエンド回路及び通信装置
KR1020217041248A KR20220008345A (ko) 2019-07-05 2020-06-25 탄성파 장치, 고주파 프론트 엔드 회로 및 통신 장치
CN202080042328.3A CN113940002A (zh) 2019-07-05 2020-06-25 弹性波装置、高频前端电路以及通信装置
US17/567,918 US12009799B2 (en) 2019-07-05 2022-01-04 Acoustic wave device, high-frequency front-end circuit, and communication device

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WO2018043610A1 (ja) * 2016-09-02 2018-03-08 株式会社村田製作所 弾性波フィルタ装置、高周波フロントエンド回路及び通信装置
WO2018070369A1 (ja) * 2016-10-11 2018-04-19 京セラ株式会社 弾性波装置
WO2018097016A1 (ja) * 2016-11-25 2018-05-31 国立大学法人東北大学 弾性波デバイス

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WO2018043610A1 (ja) * 2016-09-02 2018-03-08 株式会社村田製作所 弾性波フィルタ装置、高周波フロントエンド回路及び通信装置
WO2018070369A1 (ja) * 2016-10-11 2018-04-19 京セラ株式会社 弾性波装置
WO2018097016A1 (ja) * 2016-11-25 2018-05-31 国立大学法人東北大学 弾性波デバイス

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KR20220008345A (ko) 2022-01-20

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